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How to detect number, uppercase, lowercase data in string using JavaScript ?

Why does this code tell me $, # and ! are upper/lower case ?

How can I detect only number, uppercase, lowercase ?

https://jsfiddle.net/hqw12ov8/

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script>
var strings = 'abCD12$#!';
var i=0;
var character='';
while (i < strings.length){
    character = strings.charAt(i);
    if (!isNaN(character * 1)){
        alert('character is numric');
        alert(strings.charAt(i));
    }else{
        if (character == character.toUpperCase()) {
            alert ('upper case true');
            alert(strings.charAt(i));
        }
        if (character == character.toLowerCase()){
            alert ('lower case true');
            alert(strings.charAt(i));
        }
    }
    i++;
}
</script>
VLS
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mongmong seesee
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2 Answers2

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How can I test if a letter in a string is uppercase or lowercase using JavaScript?

This is where you have gotten the original code from correct? Here is a version that will remove the punctuation markers from this SO

How can I strip all punctuation from a string in JavaScript using regex? 

var strings = 'this iS a TeSt 523 Now!';
var punctuationless = strings.replace(/[.,\-\/#!$%\^&\*;:{}=\-_`~()]/g,"");
var finalString = punctuationless.replace(/\s{2,}/g," ");
var i=0;
var character='';
while (i <= strings.length){
    character = strings.charAt(i);
    if (!isNaN(character * 1)){
        alert('character is numeric ' + character);
    }else{
        if (character == character.toUpperCase()) {
            alert ('upper case true ' + character);
        }
        if (character == character.toLowerCase()){
            alert ('lower case true ' + character);
        }
    }
    i++;
}

I don't know if you want to include this punctuation in your check, since punctuation is neither upper or lowercase.

Community
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Chris Ryan
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In JavaScript toUpperCase() works only with lower case alphabets. Other upper case letters and non-alphabetic characters (like A, B, Y, Z, $, _ etc.) remains unchanged. So '$'.toUpperCase() returns '$'. The same happens with toLowerCase(). So when character is '$' or '#', character==character.toUpperCase() returns true.

The following code should do what you want. Here I am checking the Unicode value of each character with String.prototype.charCodeAt(index).

var strings='abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789($_)'; 
for(var i=0;i<strings.length;i++) 
{ 
var c=strings.charCodeAt(i); 
var s=strings.charAt(i); 
if(c>=48&&c<=57) 
//if(s.match(/[0-9]/))  
alert(s+' is Number'); 
else if(c>=97&&c<=122) 
 //else if(s.match(/[a-z]/))  
alert(s+' is Lower Case'); 
else if(c>=65&&c<=90) 
 //else if(s.match(/[A-Z]/))  
alert(s+' is Upper Case'); 
else 
alert(s+' is neither Number or Alphabet'); 
}

Use the lines in the comments instead of the lines before them for a simple RegExp support. It will also help to remove var c=strings.charCodeAt(i);.

Sherlock Doyle
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